BEX Query issue

Hello, I want to ask a question about front-end. When bex query is executed data will come from the infoproviders and display as rows. Is there a way that I can capture column's value row by row in a variable?  For example:

I have this report:

CostCenter Account  Creation Date      Keyfigure
101            120            01/01/2014          $100
102            121            03/03/2014          $200

I want to capture the creation date value in some variable for each row and then apply some business logic in CMOD.  but i don't know how to do that. Can some one tell me how to do that?
Thanks.